Rapid Electron Acceleration in Low-Density Regions of Saturn's Radiation Belt by Whistler Mode Chorus Waves.
Rapid Electron Acceleration in Low-Density Regions of Saturn's Radiation Belt by Whistler Mode Chorus Waves.
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惠斯勒模式合唱波在土星辐射带低密度区域的快速电子加速。
DOI：
10.1029/2019gl083071
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发表时间：
2019
影响因子：
5.2
通讯作者：
Woodfield EE
中科院分区：
文献类型：
--
作者：
Woodfield EE
由于哨声模式的合唱波，土星上的电子加速以前被认为是无效的;更接近土星的新数据显示它可以非常快（在10天内，1 MeV的通量增加了104倍，而不是2倍）。一个完整的调查合唱波在土星相结合的改进等离子体密度模型表明，在等离子体频率福尔斯低于gyrofrequency额外的强共振观察有利于电子加速。这导致在约2.5RS和5.5RS之间的强合唱加速度，在此之外绝热运输可能占主导地位。强烈的俯仰角依赖性导致蝶形俯仰角分布在几天内变平在100千电子伏，几十天在兆电子伏的能量，这可以解释观察到的蝶形分布的兆电子接近L =3。在模拟中包括交叉项会增加蝴蝶分布的趋势。
Electron acceleration at Saturn due to whistler mode chorus waves has previously been assumed to be ineffective; new data closer to the planet show it can be very rapid (factor of 104flux increase at 1 MeV in 10 days compared to factor of 2). A full survey of chorus waves at Saturn is combined with an improved plasma density model to show that where the plasma frequency falls below the gyrofrequency additional strong resonances are observed favoring electron acceleration. This results in strong chorus acceleration between approximately 2.5RSand 5.5RSoutside which adiabatic transport may dominate. Strong pitch angle dependence results in butterfly pitch angle distributions that flatten over a few days at 100s keV, tens of days at MeV energies which may explain observations of butterfly distributions of MeV electrons nearL=3. Including cross terms in the simulations increases the tendency toward butterfly distributions.